Nikon D4S: Nikon's flagship DSLR impresses

It seems as if Nikon is following Apple's iPhone naming methods. Its flagship DSLR, Nikon D4, has been updated and given the name D4S.

At first glance, D4S shares quite a few of the same features as the D4, such as the 16.2-megapixel full-frame image sensor, 91,000-pixel metering sensor, 3.2-inch fixed display and 51 autofocusing (AF) points.

D4S, however, has an upgraded Expeed 4 image processor with a maximum ISO setting increased to 409,600 (ISO 204,800 for the D4). The continuous shooting speed is slightly improved to 11 frames per second (fps), from D4's 10fps.

According to Nikon, the AF logarithms have been recalibrated in D4S for faster AF. In addition, D4S can now shoot full high-resolution (HD) videos at 60fps, twice as fast as the D4's 30fps.

The D4S also has a new RAW S file format that is half the size of standard uncompressed RAW files. For a wedding photographer, for instance, who needs to do morning shoots and rush to edit for the evening's banquet slideshow, this smaller format will speed up the workflow while not affecting image quality.

The biggest improvement is actually a downgrade of sorts.

At $8,799 (body only), the Nikon D4S costs $1,000 less than the D4 when it was first released here. Still, it is an astronomical sum to many.

For that sum, though, you get a DSLR that is built like a rock. Its weather-resistant magnesium-alloy body can really take a beating. For photojournalists working under extreme conditions, this is a camera that will not fail you.

Its generous and ergonomic rubberised grip allows you to hold the camera firmly and comfortably. The numerous buttons and dials might scare off a beginner but they are music to a professional.

The D4S retains the D4's button layout. As in professional flagship DSLRs, its Mode dial is not the kind with a mind of its own. This requires you to hold down the Mode button on top with your index finger and adjust the rear dial with your thumb to change shooting modes.

There are also controls to facilitate shooting in portrait and landscape modes: two front dials, two rear dials, two mini-joysticks for AF point control, and two AF-On buttons.

Dual memory card slots (for CF and XQD cards) make simultaneous back-up possible. You can store more images with the two memory cards, or save RAW images on one card and JPEG images on the other.

The camera starts up instantly, making sure you will not miss any decisive moments. Shutting down takes around 1sec. Shutter lag is almost non-existent.

For this review, we used a Nikon 24-85mm f3.5-4.5 lens and 70-200mm f2.8 lens. Both are FX lenses suited for full-frame DSLR.

If you use a Nikon DX lens built for APS-C DSLR, you will see a cropped frame on the viewfinder.

We also had a brief spell with the Nikon 400mm f2.8 lens shooting karting. Regardless of the lens, AF is just amazingly quick and accurate. With the 400mm lens, every picture shot during the karting in bright sunlight had the focus spot-on.

In dim light, using the 24-85mm lens, the D4S takes about 1sec to lock onto a focus, without the help of AF assist light.

Using a 16GB XQD card with a writing speed of 125MB per second and an 8GB CF card with a writing speed of 50MB per second, the D4S shot 40 images in simultaneous RAW and JPEG format (RAW saved to XQD and JPEG saved to CF) in 6.7sec before it ran out of buffer. This is an amazing performance. Using the XQD card alone, it managed 60 RAW images in 8.5sec.

While the D4's auto white balance tends towards blue under artificial lighting, the D4S has an optional auto white balance that helps to keep warm tones warm under artificial light.

If you thought the D4's noise performance was superb, the D4S' is out of this world. The images shot look clean and noiseless until ISO 6,400. Even at ISO 12,800, I can hardly see any image noise. Only at ISO 25,600 did chromatic noise artefacts and slight detail loss become evident. But I would not recommend speeds above ISO 25,600.

The full HD videos are equally great. But you have to press the AF-On button to get a focus when you pan to a new scene, and the videos tends to pick up too much ambient audio.

On the bright side, battery life is really staggering. On a full charge, it shot 3,000 images before it finally ran flat. For those out in the field for a while, this camera can go on for days if you shoot conservatively.

For Nikon D4 users, this camera may not make much sense as an upgrade. But if you really want a stupendous DSLR and can afford it, the D4S will not disappoint.